The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long period and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continents. 

句中with rising convection currents under the mid-ocean ridges and sinking currents under the continents. 做什么成分呢？书中解释是做produce的方式状语，可我感觉做方式状语理解起来怪怪的，感觉应该是用来补充说明convection的。

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